1. Field of the Invention
The present invention relates to a tubular connection, and more particularly to a tube to block connection incorporating novel self-centering features for more reliability and better fluid-tight sealing in the service life of the connection.
2. Description of the Prior Art
In assembling certain air-conditioning units, such as those used in automobiles, it is common practice to secure a tube to a female connecting block. In order to effect a fluid-tight seal between the tube and the female connecting block, an O-ring is situated in an annular groove in an end-form on the tube. Typically, the end-form of the tube is initially secured in a male connecting block and then is attached to the female connecting block by a bolt that extends through an aperture in the male connecting block and threadingly engages the female connecting block. The bolt is located adjacent but spaced away from the tube that in turn engages the female connecting block via a throughbore therein.
The bolt is caused to threadingly engage the female connecting block by applying a torque in the clockwise direction to the head of the bolt. In turn, the clockwise torque on the bolt imparts a clockwise torque on the male connecting block causing it to rotate relative to the threads of the female connecting block in the clockwise direction. Since the tube is secured within the male connecting block, the tube likewise pivots relative to the threads of the female connecting block in the clockwise direction. Because the tube is also loosely located within the female connecting block when the torque is applied to the bolt, the tube undergoes a side-loading phenomenon within the throughbore. That is, the tube and associated O-ring translate within the female connecting block and become over-compressed on one side and under-compressed on an opposite side. The resultant uneven compression on the O-ring can result in premature failure of the O-ring at the over-compressed side and leakage of fluid past the O-ring seal at the under-compressed side over the life of the tubular connection.
Accordingly, there are many examples in the prior art of apparatus to assure proper alignment of tubular connections embodying similar male and female members. One such example is disclosed in U.S. Pat. No. 4,659,116 to Cameron. The Cameron patent discloses a fitting including a male part having a contoured lead end that engages a female end having a complementary contour. The male and female parts self align as they are joined together and create a fluid-tight seal. However, the contoured surfaces of the male and female parts do not prevent off-center compression of the O-ring once the fitting is clamped together by a threaded collar.
Further, the Cameron patent is representative of the prior art, which essentially focuses on alignment of male and female members during the joining process. However, the special problem of aligning a tube within a male-female connecting block connection as described hereinabove is not addressed in the prior art. The special problem applies to the present invention where torque is applied indirectly to the tube during the joining process. None of the prior art teaches or suggests apparatus for centering a tube within a female connecting block and maintaining the centering during the application of a torque imparted to the tube.
Accordingly, what is needed is a tube to block connection that provides a tube that supports an O-ring, wherein a male connecting block encircles part of the tube, and the tube can be centered in a bore within the female connecting block. The tube remains centered during the application of a torque to a fastener in the male connecting block. The resultant centering maintains even compression of the O-ring seal. Moreover, the mating tube and female connecting block can each accommodate a greater degree of variation in size and/or shape in either or both the tube and female connecting block.